I guess I just wish it was possible for a relationship to fade away gradually like a regular friendship without having to "break up"...

Oh, I've had plenty of relationships just fade out. It can be a big relief when it happens that way. It fizzles out by just calling and seeing each other less frequently until neither one makes the effort anymore.

It usually only works in situations where things are very casual, which makes sense, right? Just letting things fade usually happens when there's not much spark, or the people are just tired of each other, or it's not very involved in the first place. It's always possible to hookup again down the road a few years, months, or whenever, as long as there're no hurt feelings left about it.

I don't know if letting it fade would work for you here, because you say you two are together all the time, and you want to stay in touch with him and maybe still get it on with him once in a while. You may just have to find the words to tell him. That being said, it's your first relationship, you've only been together a few months, and you may look back at this in the future like, "I wanted to stay in touch? Why?" Only you know what feels right for handling your situation. I would say, just be clear with yourself about what you want, as far as ending it completely or keeping possibilities open.